1. Field of the Invention
The present invention relates to microwave ovens, and more particularly, to a cooking chamber assembly in a microwave oven of which ceiling and air duct assembly are improved.
2. Background of the Related Art
The microwave oven defrosts or heats food by directing a microwave to the food, that causes molecules in the food to vibrate to generate frictional heat for the defrosting or the heating.
FIG. 1 illustrates a partly disassembled perspective view of a related art microwave oven. As shown, the microwave oven is provided with a base plate 10, a front plate 15 and a rear plate 13 mounted on a front end and a rear end of the base plate 10 vertical thereto respectively, an inner case 17 between the front plate 15 and the rear plate 13 to form a cooking chamber 20 therein, an outfit chamber 30 formed over the base plate 10 and sides of the inner case 17, a front panel 40 attached to the front plate 15, a plurality of electric components in the outfit chamber 30, and an outer case 45 for enclosing the inner case 17 and the outfit chamber 30.
The front plate has an opening 16 for making the cooking chamber 20 in communication with an exterior, and a door 41 on the front panel 40 for closing the opening 16.
The outfit chamber 30 is provided with a magnetron 31 for generating and directing a microwave to the cooking chamber 20, a transformer 32 for boosting a voltage of an external power and supplying to the magnetron 31, and a cooling fan 33 for cooling various components.
The cooking chamber 20 of the microwave oven may sometimes be provided with a ceramic tray 50 on a bottom thereof and an air duct 60 on a ceiling thereof for circulating air in the cooking chamber 20. Structures for mounting the ceramic tray 50 and the air duct 60 to the cooking chamber 20 will be described, briefly.
FIG. 2 or 3 illustrates a structure for mounting the tray 50 in the cooking chamber 20. As shown in FIG. 2, the tray 50 is mounted on the bottom of the cooking chamber 20 together with a plurality of gaskets 55. The gaskets 55, for an example, of silicone rubber, are provided to four sides of the tray 50. The gaskets 55 are put inside of the cooking chamber 20, together with the tray 50, and sealant 56 is applied to corners of the tray 50 where the gaskets 55 abut.
However, the application of the sealant is not convenient in above structure, failing to cover the abutting parts of the gaskets 55, perfectly. Then, as shown in FIG. 3, there may be a small gap 57 formed between the gaskets 55, a corner of the cooking chamber 17, and the sealant 56. Then, water or dirt may infiltrate therein, which is not sanitary, and may caused rust, or out of order of components when intensive. Moreover, the applied sealant 56 or the gap 57 harms a sense of beauty of the cooling chamber 20, and drops consumer satisfaction.
In the meantime, referring to FIG. 4, the air duct 60 is mounted on an underside of a ceiling of the cooking chamber 20. The air duct 60 draws in external air, circulates the air inside of the cooking chamber 20, for prevention of formation of dew on the door 41 during cooking, and discharging smell and smoke from food to an exterior. To do this, the air duct 60 has inlets 61 for introducing the external air passed through the outfit chamber 30 into the cooking chamber 20, and outlets 62 for drawing the air circulated inside of the cooking chamber 20 and discharging to an exterior.
Such an air duct 60, in general formed of plastic, is fastened to an underside of ceiling with fastening members 63, such as screws, as shown in FIG. 4. However, such a fastening structure requires many assembly components, and a complicated assembly process, and time, which drops productivity.